Apparatus and method for calibrating a motor monitor by reading and storing a desired value of the power factor

ABSTRACT

A monitor for an electric motor, the monitor capable of connection to a supply of electrical energy for the motor, has a microcomputer for measuring the power factor of a voltage applied to the motor and a current flowing to the motor, for storing a desired value of power factor, for comparing a measured value of power factor with the desired value of power factor, and for disconnecting the motor from the supply of electrical energy if the measured value of the power factor differs from the desired value of power factor by an amount that exceeds a predetermined amount. Further, the monitor has means for operating the motor while driving a desired load; means for commanding the microcomputer to measure a power factor of the voltage applied to the motor and the current flowing to the motor while the motor is driving the desired load; and, means for storing the measured value of the power factor, measured while the motor is driving the desired load, as the desired power factor. The monitor may control a motor driving a pump for a fluid system. The monitor may include: a pressure sensitive mechanical switch; means for measuring motor current, voltage applied to the motor, time intervals during which the motor is energized, and the rapidity of cycle time of the motor in order to disconnect the motor from the source of electrical energy to prevent damage to the motor.

This application is a continuation of application Ser. No. 512,492,filed on July 11, 1983 now abandoned.

The present invention relates to controls for electric motors and moreparticularly to a control switch having mechanical and solid statecomponents for controlling the energization of a submersible pump motor.

BACKGROUND OF THE INVENTION

Fluid pressure responsive switches are well known and have long beenused to control the energization of electric motors driving submersiblepumps that deliver fluids under pressure from a well to a receiving tankduring periods when the fluid pressure within the tank is lower than apreset pressure. An example of a control of this type is disclosed in anexpired U.S. Pat. No. 2,741,678 and a U.S. Pat. No. 3,340,372. Whilecontrols incorporating features of these patents are presentlyextensively used, in certain pumping installations pump motors may beunprotected against damage which results when the recovery rate of thewell from which the fluid is pumped is less than the rate at which thefluid is removed from the well. A pressure switch as disclosed in theU.S. Pat. No. 3,345,480 is intended to prevent motor damage under lowwater pumping conditions by permitting the motor to be energized as longas the well conditions permit the pump to maintain the fluid pressure ofthe system within a preset pressure range. The switch operates toprevent pump motor operation when the fluid level in the well is belowthe level which will permit the pump to maintain the desired systempressure. A further improvement in pressure switches for submersiblepump motors appears in a U.S. Pat. No. 4,020,308, which discloses anarrangement for providing an indicating light in a cover of a fluidpressure switch. Pressure switches of the type included in the '308patent are particularly suited for use in pumping systems where it isdesirable to visually indicate periods when the pump motor is energized.

SUMMARY OF THE INVENTION

The mechanical pressure and other switch components according to thepresent invention are housed within a single enclosure. In the preferredembodiment of the invention, the enclosure is provided by a pair ofhousing parts with one of the parts, termed the lower housing partenclosing fluid pressure responsive components and snap acting switchparts and the other or upper housing part enclosing solid state andother electrical components that are connected to terminations on thesnap switch in the lower housing parts by a separable or plug-in typeconnection to provide a convenient access to the pressure responsivecomponents and wire terminals in the lower housing part for wiring andadjustment purposes. The upper housing part encloses solid statecomponents, a relay and current and voltage detectors. The upper housingpart also includes a calibrating button which is accessible from the topor front of the upper housing part and is provided to program theoperation of the solid state circuits. The upper housing part alsopositions indicating lights which are coded to indicate the type of anoperative malfunction of the pump motor.

It is an object of the present invention to provide a control for a pumpmotor with a segmented housing wherein one segment encloses a pressureresponsive snap acting mechanism and the other segment contains solidstate switching components and to electrically interconnect the snapswitch with other components of the control by a plug-in type electricalconnection.

A further object is to provide a control for a pump motor with a housingthat encloses solid state components which are provided to monitor theoperative condition of the motor and provide the housing with a switchbutton and indicating lamps which are respectively usable to calibratethe solid state components within the enclosure and indicate theoperative state of the pump motor.

An additional object is to provide a control for a pump motor withcomponents that detect variations in fluid pressure delivered by thepump, detect when the load on the motor is less than a normal value,detect when the motor is operating under locked rotor or overloadconditions, detect when the duration of the pumping cycles areexcessively long or short and when the input voltage to the motor isexcessively high or low.

Another object is to provide a control for a pump motor with componentsthat detect and provide signals indicative of the voltage, current andpower factor of the motor current and control the operation of the motorin response to the the signals.

A still further object is to provide a control for a pump motor withcomponents that detect and provide signals indicative of the pressureoutput of a pump driven by the motor and the current and voltage as wellas the power factor of the motor current and provide a snap actingmechanical switch mechanism that is controlled by the pressure outputand a means including electronic components for controlling theoperation of the motor in response to the voltage, current and powerfactor.

Further objects and features of the invention will be readily apparentto those skilled in the art from the specification and the appendeddrawings illustrating a preferred embodiment in which a mechanicallyoperated pressure switch having solid state components incorporating thefeatures of the present invention is diagrammatically shown.

DESCRIPTION OF THE DRAWINGS

FIG. 1 and 1A are cross section elevation views of a pump motorcontroller that incorporates the present invention;

FIG. 2 is another cross section elevation view of the switch in FIG. 1;

FIG. 3 is a diagram illustrating the functional relationship of certainof the components of the control in FIG. 1;

FIG. 4 is a chart showing the interrelation of the components in thecontrol illustrated in FIG. 1.

FIG. 5 is a diagram showing the range of the operation of the control inFIG. 1.

FIG. 6 is a block diagram of a flow chart utilized by the control logicin the motor controller in FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENT

[Referring to the drawings, a control 10 incorporating a pressure switchmechanism 12 and a microprocessor type control includes mechanical andpressure responsive components as disclosed in U.S. Pat. No. 3,340,372,which was granted to Carl A. Schaefer and is incorporated herein byreference.] The control 10 is particularly suited for use in submersiblepump installations wherein a pump and a motor driving the pump aresubmersed in the fluid within a well and delivers fluid under pressureto a receptacle located above ground.

As disclosed in the Schaefer patent, the pressure switch mechanism 12includes a diaphragm mechanism 14 that is mounted on a support 16 andoperates a snap action mechanism 18 including movable contacts 20 inresponse to variations in pressure imposed on the diaphragm mechanism14. The diaphragm mechanism 14 includes a flexible diaphragm 22 that ismoved in response to variations in fluid pressure imposed thereonthrough a fluid conduct, not shown, that is connected between a fluidreceptacle, not shown, and a coupling 24. The snap acting mechanism 18includes a member 26 that moves in response to movements of thediaphragm 22 and causes a snap acting movement of a member 30. Themember 30 through an arm portion, an insulating contact carrier 66 andconducting member 68 provides a support for movable contacts 20 andcauses the contacts 20 to engage pairs of stationary contacts 32 with asnap action when the diaphragm 22 responds to a pressure less than aselected pressure. The member 30 also causes the contacts 20 to move outof engagement with the contacts with a snap action when the pressureimposed on the diaphragm 22 is greater than a preselected value.

The stationary contacts 32 are carried on an insulating terminal block34 that is in turn carried on the support 16, As most clearly shown inFIGS. 1A and 3, the stationary contacts comprises four contacts 36-39that are positioned on the block 34 as two pairs of contacts withcontacts 36 and 37 providing one pair and the contacts 38 and 39providing the second pair. The contacts 36-39 are mounted on L-shapedterminal members 40-43 respectively with each terminal member 40-43having a leg portion whereon its associated contact 36-39 is secured anda leg portion threadedly receiving terminal screws 44-47 respectively.One of the terminal members 40-43, e.g. terminal 43 is provided with abayonet connector 48 and an additional or a fifth terminal, i.e., aterminal 50 is mounted on its own individual insulating block 51 andincludes a terminal screw 52 as well as a bayonet connector 54.Additionally, one of the terminal members 40-43, e.g. terminal member 40is engaged by a prong 56 that electrically engages the terminal member40 as will be later described. The insulating block 51 is secured to theblock 34 by a screw 53.

As shown in FIGS. 1A and 3, the contact carrier 66 is substantiallyV-shaped with each of its arms carrying a bridging conducting member 68having a pair of the contacts 36-39 disposed at each end thereof. Thecontacts 36-39 are positioned to cooperate and engage adjacent pairs ofthe stationary contacts 32.

Referring to FIG. 1 and 3, the pressure switch 10 is wired when a cover70, as will be later described in detail, is removed to provide accessto the terminal screws 44-46 and the terminal screw 50. As shown, oneside of an alternating current source, not shown, is connected through aconductor 72 and tightened terminal screw 44 to the terminal 40 and theother side of the A.C. source is connected via a conductor 74 and thetightened screw 52 to the fifth terminal 50. An alternating currentmotor 76 in the embodiment disclosed herein is connected by conductors78 and 80 and tightened terminal screws 45 and 46 to the terminals 44and 42 respectively.

As more fully described in the U.S. Pat. No. 3,340,372 the support 16has a pair of posts. A range spring 79 is disposed about one of theposts 81 and a differential spring 82 is disposed about the other postof the pair. The range spring 79 has its upper end bearing against a capwasher 84 that is captivated by a nut 86 threaded on a threaded end 88of the post 81 and is used to adjust the pressure operating range of theswitch 10. The lower end of the range spring 79 abuts against andapplies a force to a free end portion of the member or lever 26 that hasrelatively large openings through which the pair of posts including thepost 81 extend. The amount of force applied by the spring 79 on thelever 26 is determined by the adjustment of the nut 86. The movement ofthe member 26 through a toggle mechanim including a toggle spring 90 istransmitted to the member 30.

As shown in FIG. 1A a post, not shown, is provided with a shoulderagainst which a cup washer 92 normally is biased by the differentialspring 82. The spring 82 is compressed by a nut 94 bearing against a cup96 which is positioned on the upper end of the spring 82.

The cover 70, in the preferred embodiment is formed of a pair of partsidentified as a rear or lower cover part 100 and a front or upper coverpart 102 which are formed as distinct parts 100 and 102 formanufacturing purposes. The cover 70 provides maximum protection tocomponents mounted within the cover 70 and accessibility to themechanical components and electrical terminations carried on the support16 and enclosed within the cover part 100. The cover part 100 has aperipheral skirt or rear end 104 positioned adjacent the peripheral edgeof the support 16 and a front wall 106 which acts as a dividing wall andseparates the interior of the cover 70 into two chambers identified as arear chamber 108 and a front chamber 110 when the cover parts 100 and102 are assembled to each other. The wall 106 includes a pair ofopenings 112 and 114 which are located to receive the bayonet connectors48 and 54 respectively and expose the ends of the connectors 48 and 54in the front chamber 110. The wall 106 also includes an opening 116which is provided in a bore extending through a post 118 that extendsrearwardly from the wall 106. The post 118 and the opening 116 arelocated to receive the prong 56 that extends rearwardly from the chamber110 through the opening 116 into engagement with the terminal 40.

The connectors 48 and 54 extend into the openings 112 and 114respectively where the connectors 48 and 54 are engaged by a pair ofspring biased plug-in connector type conductors, one of which isdesignated as 178 in FIG. 2 and represented by numerals 178 and 180 inFIG. 3. The pair of conductors 178 and 180 are secured to circuits inprinted circuit boards 176 as will be later described. The bayonetconnectors 48 and 54 as well as the prong 56 provide plug-in typeinterruptable connections and complete and interupt electric circuitswhen the cover to is removed and secured to the pressure switchmechanism 12.

The front or upper cover part 102 has a rear peripheral edge or skirt120 engaging the front side of the periphery of the wall 106 so theparts 100 and 102, when secured to each other, will provide a unitaryassembly or cover 70 which may be removed or secured as an assembly onthe support 16. To provide this assembly, the front part 102 includessuitably tapped bosses which receive screws 124, one of which is shownin FIG. 1, which secure the rear end of the front part 102 to the frontend of the part 100. When the parts 100 and 102 are assembled, the prong56 extends through the opening 116 into engagement with the terminal 40.The prong 56 preferably includes an outer cylinder that is securedthrough a member to a printed circuit board 122, positioned in thechamber 110, and a plunger that is telescoped in the cylinder andengages the terminal 40 with a spring biased pressure engagement. Alsowhen the cover parts 100 and 102 are assembled, a boss 127 extendingforwardly from the wall 106 is aligned with a boss 128 extendingrearwardly from a front wall 130 on part 102 and a bore 132 extendingthrough the bosses 127 and 128 is aligned with the front threaded end ofthe post 81. When the cover parts 100 and 102 are thus assembled, arod-like member 134 having a female threaded end 136 threaded on thepost 81 extends through the bore 132 to a threaded front end 138 thatextends through an opening in the front wall 130. A suitable nut 140when an opening in the front wall 130. A suitable nut 140 when threadedon the end 138 secures the cover 70 to the support 16.

In addition to the on and off pressure switch function provided by theswitch mechanism 12, the pressure switch 10 includes components enclosedwithin the front chamber 110 that are provided to protect the motor 76against water system failures. Among the failures to which the pumpmotor may be subjected is a condition where no load is imposed on themotor as a result of a broken pump shaft or coupling, or an insufficientwell recovery water flow, an air locked pump or a blocked pump intake.Another type of failure that can manifest itself is an overloadcondition which occurs as the pump is gradually clogged as when the pumpgradually takes up sand. Additionally, the motor may be subjected to anoverload resulting from excessive back pressure as caused by scaled andcorroded discharge pipes, a failure of the check valve to open or animproper combination of the motor and the pump because of differences intheir ratings. Other failures that may occur include extended runoperation as caused by over usage of water, worn pump parts or leaks inthe service piping and rapid cycling of the pump as maybe occasionedbecause of a water logged tank, a check valve leak or leaks in theservice piping. The components within chamber 110 are provided to detectthese failures and institute a proper response to minimize damageresulting from the failures.

The components of the control 10, as shown in FIG. 3, that are in thefront chamber 110 include a control relay 150, a current detector 152,and solid state elements identified as control logic 154. Additionally,the components include a pair of light emitting diodes (LEDS) 156 and158 and a recessed calibration switch 160 having normally open contacts.The diodes 156 and 158 as well as the recessed switch 160 are mounted inthe front wall 130 so as to be respectively visible and accessible fromthe front side of the cover 70.

Referring to the FIGS. 3 and 4, the control 10 includes the pressureswitch mechanism 12, a power supply 162, the control relay 150 havingnormally closed contacts 150a and a coil winding 150b, a currentdetector 152, a voltage detector 166, a single chip microcomputer 168,the calibration switch 160, the LED diodes 156 and 158, a non-volitilememory 170, associate control circuitry 172 and a high/low voltagedetector 174.

The power supply 162, the current detector 152, the voltage detector166, the microcomputer 168, the memory 170, the control circuitry 172are provided by solid state components mounted on printed circuit boards122 and 176, in a manner well known to those skilled in the art. Theboards 122 and 176 are maintained in parallel spaced relation by thecover 102. The relay 150 is mounted between the boards 122 and 176 andis enclosed along with the current detector 152 within the chamber 110.

The pressure switch mechanism 12 is mechanical and switches the movablecontacts 20 into a circuit closing position or a circuit openingposition in response to changes in the input pressure on the diaphragm22. When the pressure falls below a preset pressure setting, thecontacts 20 move with a snap action to a circuit closing position withthe stationary contacts 32 and the motor 76 and a pump, not shown, isenergized. The energized pump causes a pressure increase on thediaphragm 22 and the contacts 20 are moved with a snap action to acircuit opening position to deenergize the motor 76 when the pressure onthe diaphragm 22 exceeds a reset value.

As shown in FIG. 3, an alternating current source is connected viaconductors 72 and 74 to the terminals 40 and 50 respectively. Theterminal 50 is connected to the bayonet conductor 54 and componentswithin the front chamber 110 by the plug-in type connector 178. Theterminal 40 is connected to components within the front chamber 110 bythe prong 56 and the plug-in type connector 180.

The connector 54 is connected through the closed contact 150a, asuitable conductor surrounded by a pick up coil, not shown, of thecurrent detector 152 to the bayonet connector 48. The connector 54 alsosupplies an input to the control logic 154. The probe 56 is connected tothe supply lead 72 and supplies an input to the control logic 154. InFIG. 4, the pressure switch mechanism 12 is shown as having an input 162which represents the conductors 72 and 74 in FIG. 3. The mechanism 12 isalso shown as having an output 163 which represents the conductors 78and 80 in FIG. 3. The fluid pressure which is imposed upon the coupling24 in FIG. 1 is represented by the arrow 182 which desiginates thepressure imposed on the pressure switch mechanism 12. As shown in FIG.4, the power supply 162, the power relay 150, the current detector 152,the voltage detector 166, the high/low voltage detector 174, themicrocomputer 168, the non-volitile memory 170 and the control circuitry172 are all enclosed within the front chamber 110. The calibrationswitch 160 and the visual indicators 156 and 158 are positioned by thefront wall 130.

The pressure switch mechanism 12 is totally mechanical and switches thetwo sets of movable contacts 20 to energize or deenergize the motor 76in response to the input pressure 182. When the pressure 182 falls belowa low pressure setting, the contacts 20 engage the stationary contact 32and energize the motor 78. The pressure increases until a high pressuresetting is exceeded whereat the contacts 20 open with a snap action todeenergize the motor 76. The power supply 162, as included within thefront chamber 110, supplies the energizing current and voltage to theother previously mentioned components included within the front chamber110. The power relay 150 has normally closed contacts 150a in seriesbetween the connectors 54 and 48 and an operating coil 150b connected toreceive an output from the microcomputer 168. The microcomputer 168monitors the operation of the motor 76 and thereby the operation of thepump in the system. When a proper output signal is received from themicrocomputer 168, the relay 150 opens the contact 150a and therebyinhibits the pump from running even though the contacts of the switchmechanism 12 are closed due to a low pressure signal input 182. Duringnormal operation when the conditions in the the motor fluid circuit arenormal, the contacts 150a are closed. The current detector 152 includesa current transformer not shown, that converts the motor current sinewave into a logic level square wave that is inputted through a lead 184to the microcomputer 168. The edge of the output pulse from the currentdetector 152 corresponds to the zero crossing of the motor current.

The voltage detector 166 has an output 186 which is supplied as an inputto the microcomputer 168. the microcomputer 168 also receives an inputfrom the power supply 162. The voltage detector 166 converts the voltagesine wave of the A.C. supply into a logic level square wave which issupplied to the microcomputer 168. The edge of the square wave output162 corresponds to the zero crossing of the voltage across the motor 76.The microcomputer 168 is arranged to count the time interval between thezero crossing of the voltage signal on the lead 186 and the zerocrossing of the current on lead 184 and thereby provide a measure of thepower factor of the current to the motor 76.

The high/low voltage detector 174 converts the line voltage on the line162 into two logic level outputs that are supplied as an input 188 tothe microcomputer 168. The microcomputer 168 ignores the input 188 aslong as the voltage on line 162 is within preset high and low limits.When the output of the voltage detector 174 is present due to a voltagehigher or lower than the preset limits, the detector 174 through themicrocomputer 168 provides a signal to the power relay 150 which causesthe relay to open its contacts 150a and thereby deenergize the motor 76.

The microcomputer 168 is the central and controlling device in control10. The microcomputer 168 monitors the pumps operation that is conveyedby signals from the motor as previously described. The microcomputer 168provides an output to the relay 150 in response to signals indicative ofthe motor conditions as will be subsequently described.

The control 10 includes a non-volatile memory 170. The memory 170 is anEEPROM (Electrically Eraseable Programmable Read Only Memory). Thememory is of the type which will retain any information stored in it inevent of power removal or failure. An important piece of data which isto be stored in the memory 170 is the calibration value as will behereafter described. All other data values will be programmed into thememory when the control 10 is manufactured. The item designated ascontrol circuitry 172 includes components that are required to supportthe microcomputer 168, i.e., a suitable clock crystal, not shown.

The switch 160 is mounted in the front wall of the cover 70 and is thusreadily available for calibration purposes. After the electrical andplumbing connections of the pump system associated with the control 10are complete, the motor and pump are energized. When the motor isrunning under normal operating conditions, the calibration switch 160contacts are closed and an input is supplied to the microcomputer 168which jumps to a software routine and stores the calibration readingvalue in the the non-volatile memory 170 for future use. The arrangementof the switch 160 in the cover 70 is such that the switch 160 is in arecess and after the calibration procedure is completed, an adhesivesticker can be applied to the front wall 106 to conceal the switch 160.If desired, the date of calibration maybe inscribed on the appliedsticker.

The memory in which the calibration value is stored is of thenon-volitile type that does not require power to retain its data and hasits data available each time power is applied to the control 10. Thus,even if power is removed from the control 10, the calibration data inthe memory remains so that re-calibration of the switch is not required.The normal operating power factors of electric motors vary not only withload and voltage but also with the design of the motor and horsepowerrating. The calibration feature is included in the controller 10 tocompensate for these variations. According to FIG. 5, POINT A on a curve190 is a normal operating power factor or calibration value which wasentered into the memory of the control 10 when the switch 160 wasoperated. The value of POINT A on the curve 190 is used for comparisonwith an actual running power factor value, desiginated as a POINT D. Thelocation of POINT D on the curve 190 will vary for reasons such asvariations in load, voltage and pressure of the motor and pump systemand is constantly checked and compared with POINT A. When POINT D movesaway from POINT A by a plus value greater than a value "M" or less thana "N" value, the power relay 150 is energized and the motor isdeenergized and proper signals are indicated by the illuminated state ofthe diodes 156 and 158. The M and N values are fixed in the software ofthe microcomputer 168 so that normal variation in the motor operatingcharacteristics will not cause false tripping when the control 10 isproperly calibrated.

The section containing the visual indicators desiginated as diodes 156and 158 is arranged to have the diodes 156 and 158 located in the frontwall 130 so the diodes are visible from the exterior of the control 10.The light emitting diodes 156 and 158 are preferably chosen to havecontrasting colors such as a color red for the diode 156 and a yellowfor the diode 158. As shown in the table below, "F", "S" and "OFF"indicate the illuminating state or condition of the diodes 156 and 158and thereby are coded to indicate the improper operating condition ofthe motor and pump. The diodes, when operating in the manner indicated,will provide an indication of the type of failure occurring in thesystem. In the present embodiment, the coding of the diodes is asfollows with "F" indicating a flashing diode, and "S" designating adiode that is continously energized and "OFF" designating a deenergizeddiode.

    ______________________________________                                        Condition      Red LED   Yellow LED                                           ______________________________________                                        Noload         F         F                                                    Rapid Cycling  S         S                                                    Low Voltage    F         S                                                    High Voltage   S         F                                                    Overload       F         OFF                                                  Extended Run   OFF       S                                                    Normal On/Off  OFF       OFF                                                  ______________________________________                                    

When a low water condition or a motor or pump noload occurs, the powerfactor of the motor will drop below 0.45 and the motor current willdecrease. The reduced motor current reduces the urgency to deenergizethe motor and permits attempts to restart the motor several times beforethe motor is finally deenergized. When a noload condition occurs, thepump controller will detect the change in power factor and deenergizethe motor. After a short delay, the microcomputer will attempt torestart the motor. If the noload condition persists, the microcomputerwill progressively increase the delay interval of subsequent restartsand after a fixed number of preprogrammed delayed restarts, themicrocomputer will cease its attempts to restart the motor. By detectingthe power factor change, the motor is thus protected from damage. Incase of a broken shaft or plugged inlet of the pump, the motor will notbe damaged even though the pump requires service.

Overload conditions of the pump and motor may be the result of differentcauses. A motor overload occurs under locked rotor conditions and a pumpoverload occurs when an increase in back pressure causes the fluid flowof the pump to be decreased. The distinction is made between these twooverload conditions because the current and voltage parameters of themotor change differently for the two conditions and therefore differentprotection features are required to protect the pump and motor under thetwo different overload conditions. Motor overload can occur when thepump is plugged with sand or the motor is stalled. In this case, thetiming of the motor going to a locked rotor condition is the importantfactor in the protection of the pump controller. When the pump is slowlyclogged by sand, the controller will have time to detect the powerfactor increase and deenergize the motor. In contrast, when the pump andmotor are locked, the pump and motor will require a removal from thewell to clear the pump, and any protection additional to the protectionoffered by the conventional circuit breaker in the circuit would besuperflous. Additionally, if the controller did sense the locked rotoror pump plugged condition, the restarting of the pump and motor wouldaggravate the situation. For this reason, time delays and restarts arenot attempted under locked rotor or plugged pump conditions.

When the pump is subjected to an overload that is caused by excessiveback pressure, the flow output of the pump is reduced and the powerfactor and current to the motor both decrease. When this type of failureis detected, ample time will permit the motor to be deenergized beforethe pump and motor are damaged. If the pump overload conditionscontinue, a noload signal may be given because the controller cannotdistinguish between a noload and excessive back pressure conditions.

When the pump system is subjected to extended run conditions, themicrocomputer times the interval beginning with the pump energizationand if pressure is not restored within a preset time limit, a visualsignal will be given.

Rapid cycling results from a water logged tank, a check valve leak, orleaks in the plumbing. The controller 10 detects a low pressure signaland energizes the motor to restore the proper pressure. If after themotor is deenergized, a low pressure signal is prematurely detected, asignal will prevent the motor from being energized until the system isreset. This function protects the motor from overheating due to repeatedhigh starting currents in the motor. The control also detects overvoltage conditions which causes excessive stress in the motor windingsand under voltage conditions which cause overheating of the motorwindings. Good motor design dictates that a motor should not besubjected to voltages 10% greater or 10% less than its nominal voltagerating. In the controller according to the present invention when anincorrect voltage level is detected, the controller will inhibit themotor from being energized and in this manner, extend the life of themotor being controlled.

The operation of the control 10 as illustrated in FIG. 6 is believed tobe self-evident and the construction of the control to be readilyapparent to those skilled in the art to which the present inventionpertains. As shown in FIG. 3, the control logic 154 is continuouslyenergized from the source connected to conductors 72 and 74, theconnector 178 and the conductor 180. Further as shown in FIG. 4, thepower supply 162 supplies an input to the voltage detector 166 and themicrocomputer 168. The current detector 152 and the high/low voltagedetector 174 provide inputs to the microcomputer 168.

Initially, when the motor 76 is energized, as a result of a reducedfluid pressure signal 182, the output of the high/low voltage detector174 is interrogated by the microcomputer 168. If the voltage of thesupply is too low, control is transferred from a block 200 to a control202 which provides an energizing signal to the relay coil 150b todeenergize the motor 76 and provide a toggle signal which causes the redLED 156 to flash and the yellow LED 158 to have a steady glow toindicate a low voltage condition across conductors 72 and 74. If the lowvoltage condition is absent, control is transferred to the block 204 andthe control 206 which determine if the supply voltage is too high. Ifthe supply voltage is too high, a control 206 provides an output whichenergizes the relay coil 150b to deenergize the motor 76 and toggles thered LED 156 to a steady state and a the yellow LED 158 to a flashingstate to indicate a high voltage condition.

In the event a high voltage condition is not present, control transfersto a block 208 which checks if the motor 76 is operating as indicated bya proper motor current. If the motor is not running, control returns tothe block 200 via an input A to reinitiate the starting current to themotor. If the block 208 determines that the motor 76 is energized, acontrol signal is initiated after a preset time delay by a control 210that permits a block 212 to interrogate signals from the currentdetector 164 and the voltage detector 166 to determine the power factorof the motor current.

After reading of the power factor by the control 212 is inititated,control transfers to a block 214 which determines if the motor hasturned off. In the event the block 214 determines that the motor isturned off, control transfers to a block 216 that determines if theinterval of an on/off operating cycle of the motor is less than a presetvalue. In the event that the operating cycle of the motor is less thanthe preset value, control is transferred to a control 218 whichenergizes the relay coil 150b to deenergize the motor 76 and toggles thered LED 156 to a steady state and the yellow LED 158 to a steady stateto indicate rapid cycling of the motor. If the block 216 determines thatthe operating cycle is not less than the preprogrammed value, control isreturned to POINT A.

After the reading of the power factor on the motor is initiated by thecontrol 212 and the block 214 has determined that the motor is notturned off, control is transferred to a block 220 that determines if thepower factor of the motor current has been read. If the reading of thepower factor is not completed, control is returned to block 214 whichagain determines if the motor is turned off before control isretransferred to the block 220. If the reading of the power factor ofthe motor is completed, block 220 transfers control to a block 222.Block 222 determines if a calibration request has been initiated byclosure of the contacts of switch 160. In event that a a control 224which causes the entry of the parameters of the calibration into themicrocomputer 168 and returns control to the block 212 at POINT B.

In the event that a calibration value has been entered, controltransfers to a block 226. Block 226 determines if a noload condition ispresent as may be caused by a low water condition. The low watercondition is indicated by a drop in the power factor below 0.45 and amotor current decrease. When a low water condition is present, controltransfers to a block 228 that determines if the condition sensed is thefirst low water condition. If the low water condition sensed by block228 is the first low water condition, control is transferred to acontrol 230 which after a short delay energizes the relay 150 todeenergize the motor 76 and toggles the red LED 156 to a flashing stateand the yellow LED 158 to a steady state to indicate a low water ornoload condition is present. After a short delay, control is transferredfrom the control 230 to a block 232 which deenergizes the relay 150 andrestarts the motor 76. The block 228 responds to successive indicationsof a low water or noload conditions and supplies an input to a block 234for each occurrance. After the block 234 determines that four successivenoload conditions have occurred, it transfers control to a control 236which energizes the relay coil 150b and toggles the LEDS 156 and 158 toindicate a low water or noload condition is present as previouslydescribed. In the event that the condition sensed by the block 234 isnot the fourth low water condition, control is transferred to a control238 which progressively increases the delay of the signal supplied tothe block 232 as second and third low water conditions are sensed by theblock 226. Thus after four low water conditions have been sensed by theblock 226 the relay 150 is energized to interrupt the motor circuit andthe diode is energized to interrupt the motor circuit and the diode LEDS156 and 158 are energized in the manner previously described.

If the system does not have a low water or a noload condition, controlis transferred from block 226 to a block 240. If a motor and/or pumpoverload condition is present, the power factor of the motor currentwill increase above POINT C in FIG. 5 and the block 240 transferscontrol to a control 242. The overload condition causes the control 242to energize the relay 150 which deenergizes the motor 76 and toggles thered LED 156 to have a flashing output and the yellow LED 158 to be off.

If an overload condition is not present the block 240 transfers thecontrol to a block 244. Block 244 responds to a low voltage signal fromthe detector 174 and if a low voltage signal is present, transfers tocontrol via the POINT A to block 200 which energizes the relay 150 tostop the motor and toggles the red LED 156 to have a flashing output andthe yellow LED 158 to have a steady or continuous output.

In the event that the voltage detected by the block 244 is higher thanthe preprogrammed value, control is transferred to a block 246 whichinterrogates a signal from the detector 174 and supplies an outputindicating a high voltage through POINT A and through the low voltageblock 200 to the high voltage block 204. The block 204 in response tothe detected high voltage transfers control to control 206 whichenergizes the relay 150 to stop the motor 76 and toggles the LEDS sothat the red LED 156 is continuously illuminated and the yellow LED 158has a flashing output.

If the signal from the voltage detector 174 to the block 246 disclosesthat the motor is operating within the preset voltage limits, control istransferred to block 248. The block 248 times the period that the pumpis running and if the running time of the pump is excessive, control istransferred to a control 250. If the time period of the pumping cycle isexcessive, the transfer of the control to the control 250 causes thecontrol 250 to toggle the LEDS so that the red LED 156 is notilluminated and the yellow LED 158 has a steady output.

If an extended run is not detected by the block 248, control istransfered from the block 248 to the POINT B and another cycle ofinterrogating operation of the motor voltage and current in the mannerdescribed occurs.

While certain preferred embodiments of the invention have beenspecifically disclosed, it is understood that the invention is notlimited thereto, as many variations will be readily apparent to thoseskilled in the art and the invention is to be given its broadestpossible interpretation within the terms of the following claims.

I claim:
 1. In an improved electric motor monitor, the monitor capableof connection to a supply of electrical energy for the motor, having;amicrocomputer for measuring the power factor of a voltage applied tosaid motor and a current flowing to said motor, for storing a desiredvalue of power factor, for comparing a measured value of power factorwith said desired value of power factor, and for disconnecting saidmotor from said supply of electrical energy if said measured value ofsaid power factor differs from said desired value of power factor by anamount that exceeds a predetermined amount, the improvement comprising:means for operating said motor while driving a desired load; means forcommanding said microcomputer to measure a power factor of said voltageapplied to said motor and said current flowing to said motor while saidmotor is driving said desired load; and, means for storing said measuredvalue of said power factor, measured while said motor is driving saiddesired load, as said desired power factor.
 2. In an improved electricmotor monitor, the monitor capable of connection to a supply ofelectrical energy for the motor, having:a microcomputer for measuringthe power factor of a voltage applied to said motor and a currentflowing to said motor, for storing a desired value of power factor, forcomparing a measured value of power factor with said desired value ofpower factor, and for disconnecting said motor from said supply ofelectrical energy if said measured value of said power factor differsfrom said desired value of power factor by an amount that exceed apredetermined amount, the improvement comprising: said microcomputerperiodically measuring the time interval between the zero crossing of awaveform of said voltage applied to said motor and the zero crossing ofa waveform of said current flowing in said motor to determine the valueof the power factor, and the power factor is compared with the desiredpower factor; means for operating said motor while driving a desiredload; means for commanding said microcomputer to measure a power factorof said voltage applied to said motor and said current flowing to saidmotor while said motor is driving said desired load; and non-volatilememory means for storing said measured value of said power factor,measured while said motor is driving said desired load, as said desiredpower factor; at least one illuminating device externally visible andoperatively connected having coded multiple illuminating states toindicate the operating state of the motor; a power relay whichinterrupts motor current on microcomputer command if the power factorexceeds the desired power factor by a first predetermined amount, and ifthe power factor is less than the desired power factor by a secondpredetermined amount.
 3. The apparatus as in claim 2 wherein said meansfor storing a value of said power factor in a memory further comprises:amanually operated push button which, when depressed by a person, causessaid microcomputer to read a value from said means for measuring thepower factor and said microcomputer subsequently stores said value in anon-volatile digital memory.
 4. The apparatus as in claim 2 furthercomprising:a support, a pressure responsive snap acting switch mechanismmounted on the support and having terminals connected to an A.C. sourceand terminals connected to an A.C. motor, a cover having a rear endpositioned on the support, side walls extending forwardly from the rearend to a front end, a front wall extending between the front end of theside walls and a cavity extending between the support, the side wallsand front wall and enclosing the pressure responsive snap acting switchmechanism; a wall extending between the side walls dividing the cavityinto a rear chamber wherein the switch mechanism is enclosed and a frontchamber, a plurality of components including a programmablemicrocomputer chip positioned in the front chamber; and a manuallyoperable switch mounted on the front wall so that the switch is operablyaccessible to an operator, and contacts in circuit with themicrocomputer for entering electrical data relating to the motor intothe microcomputer wherein the data reflect a desired operating conditionof the motor when the motor is energized and the switch is operated. 5.The pressure switch as recited in claim 4 wherein a wall extendingbetween the side walls divides the cavity into a front chamber and arear chamber and the snap acting switch mechanism is positioned in therear chamber and the components are positioned in the front chamber. 6.The pressure switch as recited in claim 4 wherein at least oneilluminating device is positioned on the front wall and externallyvisible and connected in circuit with the components to have codedmultiple illuminating states to indicate the operating state of themotor.
 7. The apparatus as in claim 6 wherein at least one illuminatingdevice is visible externally of the front wall to indicate an operatingcondition of the motor.
 8. The apparatus as in claim 7 wherein twoilluminating devices having contrasting colors are positioned on thefront wall.
 9. The apparatus as in claim 8 wherein the terminals andcomponents are electrically connected by a separable connection.
 10. Apump and electric motor monitor for an AC electric motor driving a pumpin a fluid system, the monitor capable of connection to a supply of ACelectrical energy for the motor, comprising:a microcomputer formeasuring the power factor of a voltage applied to said motor and acurrent flowing to said motor, for storing a desired value of powerfactor, for comparing a measured value of power factor with said desiredvalue of power factor, and for disconnecting said motor from said supplyof electrical energy if said measured value of said power factor differsfrom said desired value of power factor by an amount that exceeds apredetermined amount, means for operating said motor while driving adesired load; means for commanding said microcomputer to measure a powerfactor of said voltage applied to said motor and said current flowing tosaid motor while said motor is driving said desired load; non-volatilememory means for storing said measured value of said power factor,measured while said motor is driving said desired load, as said desiredpower factor; a pressure sensitive switch having terminals connected tosaid supply of AC electrical energy and terminals connected to said ACmotor for maintaining a pressure in said fluid system within desiredupper and lower pressure limits; means for monitoring motor current andfor disconnecting said motor from said supply of AC electrical energy ifsaid current becomes outside of desired current limits; means formonitoring voltage applied to said motor and for disconnecting saidmotor from said supply of AC electrical energy if said voltage becomesoutside of desired voltage limits; a housing containing saidmicrocomputer, solid state components, and said pressure sensitiveswitch, thereby providing a fluid system monitor capable of maintainingpressure within desired limits, capable of disconnecting said motor issaid motor looses its load, capable of disconnecting said motor if saidcurrent becomes outside of desired current limits, capable ofdisconnecting said motor if said voltage becomes outside of desiredupper and lower limits, and contained within said housing.